Program switching means



June 30, 1959 1 A MEDLAR 2,892,906

PROGRAM SWITCHING MEANS Filed Sept. 18, 1957' 2 Sheets-Sheet 1 av 11/ 53 Fm. 4 I8 TZ- Z ,25 l4 GI Z 5 H B G) GS a 19 21 1 12 A5 v o 0 6 m 1 O u M 11 T Z :32 c5 10 g 3 INVENTOR LEWIS A. MEVLAR.

ATTORNEY June 30, 1959 L. A. MEDLAR 2,892,906

4 PROGRAM SWITCHING MEANS Filed Sept. 18, 1957 2 Sheets-Sheet 2 INVENTOR LEWIS A. MEDLAFZ.

FIG. \0 BY ATTORNEY PROGRAM SWITCHING MEANS Lewis A. Medlar, Oreland, Pa., assignor to Fox Products Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 18, 1957, Serial No. 684,742

7 Claims. (Cl. 200-37) This invention relates to switching apparatus and more particularly to an improved programming device capable of connecting a plurality of electrical devices to a circuit sequentially each for a definite time period.

In program switching devices, and particularly when dealing with such devices which operate at a very slow rate, a serious contact burning problem is often encountered. Considering, for example, an application in the battery charging field where a plurality of batteries are charged in sequence each for a period, say, of 10 hours out of each 100 hours, the program switch means employed may, for example, complete only one cycle of operation each week. In such a case, the movable contact of the program switch will obviously make" and break at a very slow rate, and the contact burning problem is so serious that the contact life is greatly reduced.

An object of the present invention is to provide a program switching device in which this contact burning problem is substantially eliminated.

Another object is to devise such a switching means which is capable of handling a relatively large number of circuits, yet is unusually compact and relatively inexpensive to manufacture.

In general, the invention employs the combination of a slow rate selector switching means with a fast-acting timing switch, the selector switching means comprising two assemblies actuated in out of phase relationship such that one assembly makes just before the other breaks, the timing switch operating in such manner as to remove one selector switching assembly from the switching circuit just before that assembly breaks and to simul-' tan'eously connect the other selector switching assembly in the switching circuit. In this manner, the selector switching assemblies are always electrically inactive during their contact making and breaking actions.

In order that the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

Fig. 1 is a side elevational view of a device constructed in accordance with one embodiment of the invention;

Fig. 2 is a sectional view taken on line %-2, Fig. 1;

Fig. 3 is a top view of the fast acting timing switch employed in the device of Fig. 1;

Fig. 4 is a sectional view taken on line 44, Fig. 2;

Fig. 5 is a detail sectional view taken on line 5-5, Fig. 2;

Fig. 6 is a sectional view taken on line 66, Fig. 1;

Fig. 7 is an elevational view of an end frame plate of the device of Fig. 1;

Fig. 8 is an end elevational view of a rotary cam and contact assembly employed in the device of Fig. 1;

Fig. 9 is a side elevational view of such assembly; and

Fig. 10 is a diagrammatic view illustrating the relative out of phase relationship of the rotary selector switch contacts of the device of Fig. 1.

States Patent Referring now to the drawings in detail, and first to Fig. 1 thereof, it will be seen that the embodiment of the invention here illustrated includes a shaft 1 journalled in end frame plates 2, 3 and driven through gear reduction unit 4 by a constant speed electric motor 5 the output shaft of which is equipped with a slip clutch. End plate 2 is secured, as by screws 6, to the face of unit 4 and is provided with an annular central boss 7 surrounding the output shaft 8 of the gear reduction unit and embracing an end portion 9 of shaft 1, as best seen in Fig. 9. To obtain a firm driving connection between shaft 1 and output shaft 8 of the gear reduction unit, shaft 8 is provided with a flattened end engaged in a slot 1 Fig. 9, in shaft 1. End plate 2 is also provided with a plurality of offset portions 10, spaced circumferentially at the edge of the plate, as seen in Fig. 7. Similarly, the other end plate 3 has an annular central boss 11 embracing an end portion 12 of shaft 1. Plate 3 also is provided with a plurality of circumferentially spaced, offset portions 13. Offset portions 10, on plate 2, and 13, on plate 3, are directed toward each other, as seen in Fig. 1.

Disposed against offset portions 10 and 13, respectively, and spaced apart by spacer elements 14, are insulating discs 15 and 16. The end plates 2, 3 and insulating discs 15, 16 are secured in place by screws 17 extending through offset portions 10, 13 of the end plates and threaded into the ends of spacer elements 14.

As seen in Fig. 2, insulating disc 15 carries, on the face thereof directed toward disc 16, a series of radially directed, circumferentially spaced fixed selector switch contact elements 18-23. Such contact elements are advantageously formed from sheet brass and, as seen in Fig. 5, are provided at their inner ends with fingers 24 extending through apertures in disc 15 and crimped therebehind to secure the contact elements rigidly in place. On the same face of disc 15 is an additional contact element 25, also formed of sheet brass, and secured in place by fingers at 26, 27 extending through and bent behind the disc 15. Contact element 25 is generally annular in form and includes a plurality of extensions 28-33 directed radially outwardly and disposed between adjacent ones of the inner ends of contact elements 18-23. The annular series of contact elements 18-23 and annular contact element 25 are concentric with shaft 1.

Referring to Fig. 6, insulating disc 16 is provided, on the face thereof directed toward disc 15, with an annular series of circumferentially spaced, radially directed fixed selector switch contact elements 34-39, secured to disc 16 in the same manner hereinbefore explained with reference to Fig. 5. Also fixed to the same face of disc 16 is an additional annular contact element 40, provided with extensions 41-46 extending radially outwardly and disposed between adjacent inner ends of fixed contact elements 34-39.

Secured to shaft 1 midway between discs 15 and 16, and disposed transversely of the shaft and parallel to the discs, is a timing cam 47, Figs. 1, 8 and 9. As seen in Fig. 8 there is secured to the face of cam 47 adjacent disc 15 a rotary selector switch contact 48 having an annular central portion 49, a longer contact finger 50 of contact element 25. Rotary contact 48 is formed from thin, spring, sheet metal and has a normally curved form, being bent about a central line extending at right angles to fingers 50, 51. This curved form is such that the normal axial distance between the center of contact 48 and the working surface of tips 52, 53 is greater than the axial distance between contacts 18-23 and cam 47. Accordingly, with the device assembled in the manner seen in Fig. 1, tips 52 and 53 are urged against contacts 18-23 and 25, respectively, by spring action. To accommodate irregularities between contact elements 18- 23 and extensions 28-33, finger 50 of rotary contact 48 is centrally slotted, at 54-. Rotary contact 48 is fixed to cam 47, as by fingers at 55 bent at right angles to central portion 49 and embedded in the material of the cam.

Secured in the same manner to the opposite face of cam 47 is a second rotary selector switch contact 56 having precisely the same configuration as contact 48 but facing in the opposite direction, that is, toward disc 16, and being angularly displaced from contact 48, in the direction of rotation of the cam, by 90. Tip 57 of longer finger 58 of contact 56 is thus disposed to sweep the inner ends of fixed contact elements 34-39 and the outwardly directed extensions 41-46 of contact element 40. Tip 59 of shorter finger 60 of contact 56 is disposed to he constantly in engagement with the annular body of contact element 40.

Rotary contacts 48, 56 are non-shorting, that is, their contact tips are incapable of bridging between adjacent ones of the fixed contact elements.

Since rotary selector switch contacts 48 and 56 are angularly displaced from each other by 90, these contacts are always out of phase with each other during the selector switching operation. Thus, as illustrated in Fig. 10, as tip 52 of longer finger 50 of contact 48 comes into engagement with fixed contact element 19, for example, tip 57 of longer finger 58 of contact 56 has begun to disengage from fixed contact element 23 but has not actually broken contact therewith. At the instant electrical contact between tip 57 and element 23 is broken, good electrical contact between tip 52 and element 19 already exists. It may thus be said that one of the rotary selector switch contacts breaks just after the other makes, though the term just after must of course be construed as relative in cases where the speed of rotation of contacts 48 and 56 is very slow. When. one of the rotary contacts 48, 56 is between adjacent fixed contact elements, the other rotary contact is always in engagement with a fixed contact element. Because of the configuration of the contact assemblies, there are periods when both movable contacts 48, 56 are engaging fixed contact elements.

Like insulating discs 15 and 16, cam 47 is fabricated from suitable electrical insulating material, such as a phenolic resin-fabric laminate.

From Figs. 2 and 4, it will be noted that finger 27, punched out of extension 33 of contact element 25, engages behind a metal strip 61 which extends radially out- Wardly past the periphery of insulating disc 15 and thence parallel to shaft 1 and toward disc 16. At its free end, strip 61 is provided with a contact 62 forming one fixed contact of a single pole, double throw snap switch indicated generally at 63. Similarly, insulating disc 16 carries a second metal strip 64 electrically connected in the same manner to extension 46 of contact element 40, strip 64 extending through disc 16 at a point radially inward of contact 62, and being directed toward disc 15. Here, the strip 64 is provided with a contact 65 which forms the second fixed contact of snap switch 63. Since rotary selector switch contacts 48 and 56 are always in engagement with contact elements 25 and 40, respectively, contact 62 of switch 63 is always connected electrically to rotary contact 48 and contact 65 to rotary Contact 56.

As seen in Fig. 2, switch 63 is mounted on a bracket 66 carried "by the discs 15 and 16 and comprises a spring actuating member 67. The latter has one end fixed in insulating mounting means 68 and terminates at the other end in a portion 69 oifset toward shaft 1 and disposed for constant engagement with the periphery of cam 47. The central portion of actuating member 67 is cut out, providing arms 67, 67 Fig. 3, disposed one on each side of a spring finger 70 carrying the movable contact 71 of switch 63. One end of finger 70 is fixed in mounting means 68; the other has a tongue engaged in a slot in one end of a bow spring 72. The other end of how spring 72 is provided with a slot in which is engaged a tongue on actuating member 67.

In operation of snap switch 63, contact 71 engages contact 62 when the end portion 69 of actuating member 67 engages a low portion of the peripheral surface of cam 47. As a high portion of the cam. comes into engagement with portion 69 of the actuating member, the actuating member is raised until arms 67*, 67 pass spring finger 70. At this instant, bow spring 72 snaps finger 70 downwardly until contact 71 engages contact 65. The operation of the switch is of course reversed when portion 69 of actuating member 67 again finds a low portion of cam 47 Cam 47 is provided with six high portions 73 and-six low portions 74. As seen in Fig. 8, tip 52 of rotary selector switch contact 48 is centered on a low portion 74 of the cam. The cam is of such dimension that tip 57 of contact 56, being oitset from contact 48 by is centered upon a high portion of the cam. Switch 63 is so positioned with respect to the series of fixed selector switch contacts 18-23 that a high point of the cam actuates switch 63 each time one of the rotary selector switch contacts has come into good electrical contact with a fixed selector switch contact element. In this regard, it is to be noted that the individual contact elements 34-39 are aligned axially with the individual contact elements 18-23. The number of fixed selector switch contact elements in each set thereof is equal to the number of high portions of the cam. All of the fixed selector switch contact elements have the same dimension, in the direction of rotation of the cam, at the point at which such contact elements are engaged by the rotary selector switch contacts. The circumference of cam 47 is of such, dimension that snap switch 63 will be actuated twice during the time required for rotary contact 48, or 56, to sweep one fixed selector switch contact element 18-23, or 34-39, this time being determined by the width of the rotary contact tips 52, 57 and with the width of the fixed selector switch contact elements.

The position of switch 63 with respect to fixed contact elements 18-23 and 34-39 assures that switch 63 will be actuated by a low portion of the cam 47 to bring contacts 71 and 62 into engagement at a time immediately after rotary contact 48 has come into engagement with a fixed contact element 18-23. At this instant, rotary contact 56 is still in engagement with a fixed contact element 34-39. During the period of engagement between contacts 71 and 62, rotary contact 48 continues in engagement with said one fixed contact element, but rotary contact 56 leaves the fixed contact element with which it was engaged. Thus, contact 56 breaks only at a time after it has been electrically deactivated by snap switch 63. As the next high portion of cam 47 engages the actuating member 67, the operation is reversed, and rotary contact 48 is electrically deactivated during the period when it breaks with one fixed contact element 18-23 and moves into engagement with the next.

It will be obvious from the foregoing that the specific structural details of snap switch 63 form no part of the invention, it being only necessary that switch 63 be a fast-acting single pole double throw switch capable of being actuated by cam 47.

The shaft, 1 is extended beyond end plate 3 and has secured thereto a manual operating knob 75 bywhich the operator can actuate the device at will. In order that the position of the rotary selector switch contact with respect to the fixed selector switch contacts can be determined visually, knob 75 is provided with a pointer cooperating with suitable indicia on dial 76, the indicia consisting of an annular series of marks corresponding to contact elements 18-23, and of course to contact elements 34-39, since the two groups of fixed contacts are axially aligned. Thus, the pointer of knob 75 indicates the first mark of such series when contact 48 is in engagement with fixed contact element 18, for example, the second when contact 56 is in engagement with contact element 34, the third when contact 48 is in engagement with contact element 19, and so forth.

The invention is particularly useful in storage battery charge maintainers of the type disclosed in my copending application, Serial Number 684,799, filed September 18, 1957. In such an application, one side of the charging circuit is connected to the connector terminal 77 of snap switch 63, and twelve batteries to be sequentially charged are connected between the other side of the charging circuit and the various fixed contact elements 1823 and 3439. Rotary selector switch contact 48 then handles one group of six batteries and the other group of six batteries is handled by rotary selector switch contact 56, one battery being connected to the charging circuit at all times. It is obvious that, while the illustrative embodiment of the invention here disclosed provides two groups of fixed selector contacts each containing siX contacts, the structure is notlimited to-this-number.

I claim:

1. In a program switching device, the combination of two selector switching assemblies each comprising a series of fixed contacts a'nd a separate movable contact cooperating with each series; means connected to said movable contacts to drive the same at the same speed to engage the fixed contacts of the corresponding series successively, said movable contacts being connected to said means in out of phase relation such that the movable contact of one of said selector switching assemblies disengages from a fixed contact only after the movable contact of the other of said selector switching assemblies has engaged a fixed contact, there thus being successive time periods during operation of said selector switching assemblies when both of said movable contacts are in engagement with a fixed contact of their respective assemblies; a single pole double throw fast-acting switch having two fixed contacts; means connecting the two fixed contacts of said fast-acting switch each to a different one of the movable contacts of said selector switching assemblies; actuating means operatively associated with said fast-acting switch to actuate the single pole thereof alternately into engagement with said two fixed contacts, and means driving said actuating means in timed relation with the movement of said movable contacts such that said fast-acting switch is actuated only when both of said movable contacts engage a fixed contact.

2. In a programming device for connecting a plurality of electrical devices sequentially to an electrical circuit each for a predetermined time period, the combination of two sets of fixed selector contacts each connectable to a different device of two groups of such electrical devices; two separate movable selector switch contacts each operatively associated in non-shorting relation with a different one of said sets of fixed selector contacts to engage the individual contacts of such set in sequence; operating means connected to said movable contacts to actuate the same in out of phase relation such that when one of said movable contacts occupies a position in which it engages no fixed contact the other of said movable contacts always occupies a position in which it engages a fixed contact, there being time periods during the operation of said movable contacts when both of said movable contacts engage a fixed contact; and timing means comprising an intermediate circuit, fast-acting means for completing said intermediate circuit alternately to one and then the other of said movable selector switch contacts, and means for actuating said fast acting means to accomplishing such alternate completion of said intermediate circuit, said actuating means being operatively associated with said operating means to function in timed relation therewith such that said fast-acting means is actuated only when both of said movable contacts are in engagement with one of said fixed selector contacts.

3. In a program switching device, the combination of a rotary shaft, two sets of circumferentially spaced, fixed, selector switch contacts, two independent rotary selector switch contacts connected to said shaft for rotation there by and each disposed to sweep a different one of said sets of fixed selector switch contacts, said rotary contacts being angularly displaced one from the other in the direction of their rotation to an extent such that one rotary contact disengages from a fixed contact of its cooperating set of fixed selector switch contacts only after the other rotary contact has engaged a fixed contact of its cooperating set of fixed selector switch contacts, a timing cam mounted on said shaft and having a peripheral cam surface, a fast-acting switch having a movable contact and two fixed contacts, means connecting the two fixed contacts of said fast-acting switch electrically each to a different one of said rotary selector switch contacts, and means mounting said fast-acting switch adjacent said cam, said fast-acting switch including an actuating member disposed in operative engagement with said cam and said cam having a series of spaced switchactuating portions arranged to actuate the movable contact of's'aid fast-acting switch alternately into engagement with the fixed contacts thereof with such actuation occurring only when said rotary selector switch contacts both engage a fixed contact.

4. In a program switching device, the combination of a rotary shaft, two sets of circumferentially spaced, fixed, selector switch contacts, two independent rotary selector switch contacts mounted for rotation with said shaft and each having a contact portion disposed to sweep a different one of said sets of fixed selector switch contacts, the contacts of each set of fixed selector switch contacts being equally spaced and having substantially the same dimension in the direction of rotation of said shaft at the point of their engagement by the corresponding rotary selector switch contact, said rotary selector switch contacts being angularly displaced one from the other in the direction of their rotation to an extent such that one rotary contact makes before the other breaks, a cam mounted for rotation by said shaft and having a peripheral surface comprising a plurality of alternately arranged high and low portions, and a fastacting switch having a movable contact, two stationary contacts and means for actuating said movable contact alternately into engagement with said stationary contacts, said stationary contacts each being connected to a different one of said rotary selector switch contacts and said fast-acting switch being mounted with said actuating means in operative engagement with the peripheral sur face of said cam, said rotary selector switch contacts and said alternate high and low portions of the cam being so angularly related that said cam actuates said fast-acting switch to bring the movable contact thereof into engagement with one of said stationary contacts only after the rotary selector switch contact connected to said one stationary contact has moved into engagement with a fixed selector switch contact.

5. In a program switching device, the combination of frame means including a pair of spaced insulating members; a shaft rotatably mounted on said frame means and extending through said insulating members at right angles thereto; two sets of fixed selector switch contacts each mounted on a different one of said insulating members, the contacts of each such set being arranged in an annular series concentric with said shaft; a rotary cam mounted on said shaft between said insulating members and fabricated from insulating material, said cam having a peripheral surface including a series of alternately arranged high and low portions, the number of said high portions being equal to the number of fixed selector switch contacts in one of said sets; two independent rotary selector switch contacts each mounted on a different face of said cam and each having a contact portion disposed to sweep a different one of said sets of fixed selector switch contacts and thereby successively engage the individual contacts of such set, said rotary selector switch contacts being angularly displaced one from the other in the direction of rotation of said shaft to an extent such that one rotary contact makes before the other breaks; a fast-acting switch having a movable contact, two stationary contacts and actuating means for actuating said movable contact alternately into engagement with said stationary contacts, and means electrically connecting the stationary contacts of said fast-acting switch each to a different one of said rotary selector switch contacts, said fast-acting switch being mounted on said frame means with said actuating means operatively engagingthe peripheral surface of said cam, said rotary selector switch contacts and said alternate high and low portions of the cam being so angularly related that said cam actuates said fast-acting switch to bring the movable contact thereof into engagement with one of the stationary contacts of the fast-acting switch only after the rotary selector switch contact connected to said one stationary contact has moved into engagement with a fixed selector switch contact.

6. A program switching device in accordance with claim 4 and further comprising a slow speed rotary power device connected to drive said shaft, and additional manual means arranged to rotate said shaft'independently of said power device.

7. In a program switching device, the combination of a rotary shaft; two sets of fixed contacts, said contact sets being spaced apart axially of said shaft and each comprising a plurality of contacts spaced annularly about the axis of said shaft; a rotary cam mounted on said shaft between said fixed contact sets and having a peripheral surface comprising a plurality of alternately arranged high and low portions; two independent rotary selector switch contacts each mounted on a different side face of said cam and each having a contactportion disposed to sweep a different one of said sets of fixed contacts, said rotary selector switch contacts being angularly displaced one from the other in the direction of their rotation to an extent such that one rotary contact makes before the other breaks, said rotary selector switch contacts being electrically insulated from each other; and a fast-acting switch having a movable contact, two stationary contacts and means for actuating said movable contact alternately into engagement with said stationary contacts, said stationary contacts each being connected to a different one of said rotary selector switch contacts an dsaid fast-acting switch being mounted with said actuating means in operative relation to the peripheral surface of said cam said rotary selector switch contacts and said alternate high and low portions of the cam being so angularly related that said cam actuates said fast-acting switch to bring the movable contact thereof into engagement with one of said stationary contacts only after the rotary selector switch contact connected to said one stationary contact has moved into engagement with a fixed selector switch contact.

References Citedin thefile of this patent UNITED STATES PATENTS 1,340,039 Fuller May 11, 1920 1,821,559 Mau Sept. 1, 1931 1,841,519 Berkeley Jan. 19, 1932 1,980,700 Rosen Nov. 13, 1934 2,163,919 Siegel June 27, 1939 2,209,084 Foster July 23, 1940 2,646,484 Vaksvik July 21, 1953 2,685,625 Holstein Aug. 3, 1954 2,792,174 Sutter May 14, 1957 

